Polishing pad and forming method

ABSTRACT

A polishing pad which ensures that a work can be easily removed from the polishing pad surface after polishing, the amount of a polishing liquid used for polishing can be reduced, and the production cost of the polishing pad can be lowered. A first polishing pad ( 1 ) for polishing a work is provided with a plurality of slots ( 11 ) piercing the first polishing pad ( 1 ) in a sa direction, the length in the longitudinal direction of the slots ( 11 ) being preferably not less than 20 mm, the pitch in the width direction of the slots ( 11 ) being preferably less than 100 mm, and small holes (not shown) may be provided in addition to the slots ( 11 ).

TECHNICAL FIELD

The present invention relates to a polishing pad, a polishing apparatusand a polishing method, and particularly to a polishing pad providedwith a plurality of slots, a polishing apparatus using the polishingpad, and a polishing method using the polishing pad.

BACKGROUND ART

As Related Art 1, there have been commercialized polishing pads whichare provided grooves in the surface thereof. For example, there isavailable the polishing pad IC1000-A22 produced by Rodel Nitta Company.As shown in FIG. 9, this polishing pad 61 is provided in its polishingpad surface 61S with grooves 62, 2 mm in width, in a lattice pattern ata pitch of about 2 cm. Incidentally, the grooves 62 are omitted in theplan view.

As Related Art 2, there have been commercialized polishing pads providedwith a plurality of small holes (for example, small holes of 1.8 mm indiameter) in the surface thereof. One example known of this type ofpolishing pads is the polishing pad IC1000(p) produced by Rodel NittaCompany.

As Related Art 3, there has been disclosed, as shown in FIG. 10, apolishing pad 71 which is provided with a plurality of holes 72 and witha plurality of grooves 73 in its surface 71S. Incidentally, the holes 72and the grooves 73 are omitted in the plan view. No description is givenabout the diameter of the holes in Japanese Patent No. 3042593.Generally, however, the polishing pads provided with holes of 1.8 mm indiameter in a density of about 3 to 5 pieces/cm² are often used.Incidentally, it is described in Japanese Patent No. 3042593 that thewidth of the grooves may be not more than the diameter of the holes,that the depth of the grooves may be about 0.3 mm, and that the groovedepth may be up to 0.5 mm (see, for example, Patent Document 1).

In the polishing pad according to Related Art 3, provision of the holesrestrains the polishing resistance from increasing. In addition, withthe grooves formed in the polishing pad surface, the hermetic sealproperty between the polishing pad surface and a semiconductor wafer islowered, so that a negative pressure is less liable to be generatedthere. Therefore, it is easy to remove the semiconductor wafer from thepolishing pad surface after completion of the polishing. Besides, thepolishing pad according to Related Art 3 has the characteristic featuresthat the strength of the hard layer is restrained from being lowered,the load on the soft layer is reduced, and deterioration thereof withtime is suppressed, as compared to the polishing pads provided withordinary grooves.

In addition, chemical mechanical polishing (hereinafter referred to asCMP) has been used, for example, at the time of planarizing the surfaceof an insulation film in the manufacturing process of a semiconductordevice, and at the time of removing surplus materials in the formationof copper wirings, tungsten plugs or the like.

A CMP apparatus which has been widely used has a structure in which thepolishing surface of the polishing pad is planar, the surface to bepolished of a wafer and the polishing surface of the polishing pad aredisposed parallel to each other, and they make contact while beingrotated respectively, whereby polishing is performed (see, for example,Patent Document 2).

Furthermore, there have been known a belt-type CMP apparatus (see, forexample, Patent Document 3), (see, for example Patent Document 4), arectilinear oscillation type CMP apparatus (see, for example, PatentDocument 5), a CMP apparatus comprising a ring-shaped polishing pad(see, for example, Patent Document 6), and a roller-type CMP apparatus(see, for example, Patent Document 7). In every one of theabove-mentioned polishing apparatuses, the polishing surface of thepolishing pad brought into contact with the surface to be polished isplanar.

Patent Document 1: Japanese Patent Laid-open No. Hei 9-117855 (p. 4,FIG. 1, FIG. 5)

Patent Document 2: Japanese Patent Laid-open No. 2000-218514 (p. 4, FIG.5)

Patent Document 3: Japanese Patent Laid-open No. 2000-218514 (p. 4, FIG.6)

Patent Document 4: Japanese Patent Laid-open No. Hei 8-52652 (pp. 5-6,FIG. 1)

Patent Document 5: Japanese Patent Laid-open No. Hei 8-52652 (p. 8, FIG.10)

Patent Document 6: Japanese Patent Laid-open No. Hei 11-31671 (p. 5,FIG. 1)

Patent Document 7: Japanese Patent Laid-open No. Hei 2-139172 (pp. 3-5,FIGS. 1 to 3)

However, the polishing pad according to the above-mentioned Related Art1 has the problem that the polishing liquid would flow out through thegrooves during polishing, and a large amount of the polishing liquid isneeded. Besides, since the grooves are formed by cutting, the productioncost of the polishing pad is higher, as compared with polishing padswhich are provided with holes by punching.

The polishing pad according to the Related Art 2 has the disadvantagethat the polishing resistance is raised because a negative pressure isgenerated between the polishing pad and the work in the areas of theholes. Furthermore, it is difficult to remove the work from thepolishing pad after completion of the polishing. A detailed descriptionof this phenomenon is given also in Japanese Patent Laid-open No. Hei9-117855.

The polishing pad according to the Related Art 3 has the drawback thatthe production cost thereof is high, since the grooves must be formed bycutting after the formation of the holes by punching.

The problems involved in the polishing pads as above-mentioned cannot besolved by the polishing apparatuses and polishing methods using thepolishing pads described in the above-mentioned Related Arts.

DISCLOSURE OF INVENTION

The present invention pertains to a polishing pad, a polishingapparatus, and a polishing method invented for solving theabove-mentioned problems.

The first polishing pad according to the present invention is apolishing pad for polishing a work, which is provided with a pluralityof slots piercing through the polishing pad in the thickness direction.

In the first polishing pad, since the plurality of slots piercingthrough the polishing pad in the thickness direction are provided, thehermetic seal property between the surface to be polished and thepolishing pad surface is lowered, so that a negative pressure is lessliable to be generated there. Accordingly, it is easy to remove the workfrom the polishing pad surface after completion of polishing. Inaddition, since the slots formed in the polishing pad according to thepresent invention can be formed by punching, the polishing pad is lowerin production cost than a polishing pad provided with grooves formed bycutting.

The second polishing pad according to the present invention is apolishing pad for polishing a work, which is provided with a pluralityof holes piercing through the polishing pad in the thickness direction,part of the plurality of holes being composed of slots.

In the second polishing pad, since the plurality of holes piercingthrough the polishing pad in the thickness direction are provided andpart of the plurality of holes are composed of clots, the hermetic sealproperty of between the surface to be polished and the polishing padsurface is lowered due to the presence of the slots and a negativepressure is less liable to be generated there, in the same manner as inthe case of the first polishing pad. Therefore, it is easy to remove thework from the polishing pad surface after completion of polishing.Further, since a plurality of holes other than the slots are provided,the polishing resistance is restrained from increasing. Furthermore,since grooves are not provided in the present polishing pad, unlike therelated-art polishing pads, there is no possibility that a polishingliquid might flow out through grooves to the exterior of the polishingpad. The slots formed in the polishing pad according to the presentinvention reserve the polishing liquid therein, which makes it possibleto reduce the amount of the polishing liquid used. In addition, sincethe plurality of holes inclusive of the slots which are formed in thepolishing pad according to the present invention can be formed by asingle punching operation, the polishing pad is lower in production costthan the polishing pads provided with grooves which are formed bycutting. Further, since the slots are so formed as to pierce through thepolishing pad in the thickness direction, the slots are not lost evenwhen the polishing pad is worn as polishing proceeds. Accordingly, thepolishing pad according to the present invention can show a longer padlife, as compared with the polishing pads provided with grooves.

A polishing apparatus according to the present invention is a polishingapparatus which uses a polishing pad according to the present invention,whereby the production cost of the polishing pad can be lowered. Since apolishing pad according to the present invention is thus used, theoperating cost of the polishing apparatus is lowered. Furthermore, sincethe polishing pad according to the present invention has a longer padlife than that of a related-art polishing pad provided with grooves, thefrequency of replacement of the polishing pad is reduced.

A polishing method according to the present invention is a polishingmethod in which a polishing pad according to the present invention isused, whereby the production cost of the polishing pad can be lowered.Since a polishing pad according to the present invention is thus used,polishing cost is lowered. Furthermore, since the polishing padaccording to the present invention has a longer pad life than that of arelated-art polishing pad provided with grooves, the frequency ofreplacement of the polishing pad is reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a plan view and a partly enlarged view illustrating a firstembodiment of the first polishing pad according to the presentinvention.

FIG. 2 shows a plan view and a partly enlarged view illustrating a firstembodiment of the second polishing pad according to the presentinvention.

FIG. 3 is a plan view showing an embodiment of slots formed in the firstand second polishing pads according to the present invention.

FIG. 4 is a plan view showing another embodiment of slots formed in thefirst and second polishing pads according to the present invention.

FIG. 5 is a plan view illustrating a second embodiment of the firstpolishing pad according to the present invention.

FIG. 6 shows a plan view illustrating a second embodiment of the secondpolishing pad according to the present invention.

FIG. 7 is a schematic configurational perspective view illustrating anembodiment of the first polishing apparatus according to the presentinvention.

FIG. 8 is a schematic configurational perspective view illustrating anembodiment of the second polishing apparatus according to the presentinvention.

FIG. 9 shows a plan view, a partly enlarged view and a sectional viewalong line A-A′ illustrating a polishing pad according to Related Art 1.

FIG. 10 shows a plan view, a partly enlarged view and a sectional viewalong line B-B′ illustrating a polishing pad according to Related Art 3.

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment of the first polishing pad according to the presentinvention will be described referring the plan view and the partlyenlarged view shown in FIG. 1.

As shown in FIG. 1, the first polishing pad 1 is provided with aplurality of slots 11 piercing through the polishing pad 1 in thethickness direction, the slots 11 being aligned in the row direction andthe column direction. The polishing pad 1 is formed of a resin, forexample, foamed polyurethane or urethane. Its thickness is comparable tothose of ordinary polishing pads, and is, for example, about 0.5 to 3.0mm. The slots 11 are so formed as to be included in the polishing pad 1,and their length L in the longitudinal direction is not less than 20 mm.In addition, the slots 11 are formed at a pitch p which is not less thantwice the length in the transverse direction (hereinafter referred to asthe width) W thereof and is less than 100 mm. Incidentally, the spacingd in the longitudinal direction of the slots 11 is appropriately set;here, as an example, the spacing d is 10 mm. Besides, the slots 11 maybe formed to be staggered from each other in either one or both of therow direction and the column direction.

Since the first polishing pad is provided with the plurality of slots 11piercing through the first polishing pad 1 in the thickness direction,the hermetic seal property between the surface to be polished and thesurface of the polishing pad 1 is lowered and a negative pressure isless liable to be generated there, so that it is easy to remove the workfrom the surface of the polishing pad 1 after completion of polishing.In addition, the slots 11 formed in the first polishing pad 1 accordingto the present invention can be formed by punching, the polishing pad 1is lower in production cost than a polishing pad provided with groovesby cutting. Further, since the slots 11 are so formed as to piecethrough the first polishing pad 1 in the thickness direction, the slots11 are not lost even when the first polishing pad 1 is worn. Therefore,the first polishing pad 1 can show a prolonged pad life, as comparedwith the related-art polishing pads provided with grooves.

Next, a first embodiment of the second polishing pad according to thepresent invention will be described referring to the plan view and thepartly enlarged view shown in FIG. 2. Incidentally, small holes areomitted in the plan view.

As shown in FIG. 2, the second polishing pad 2, like the first polishingpad 1, is provided with slots 11 piercing through the second polishingpad 2 in the thickness direction in the state of being aligned, forexample, in the row direction and the column direction, and is providedwith a plurality of holes (hereinafter referred to as small holes) 21piercing through the second polishing pad 2 in the thickness directionand having a diameter D of 10 mm or below, preferably, 5 mm or below.Specifically, the slots 11 are included in the polishing pad 1, and havea length L of not less than 20 mm. In addition, the slots 11 are formedat a pitch p1 of not less than twice the width W thereof and less than100 mm. Incidentally, the spacing d in the longitudinal direction of theslots 11 is appropriately set; here, as an example, the pitch p1 is 10mm. In addition, the slots 11 may be formed to be staggered from eachother in either one or both of the row direction and the columndirection.

Further, the small holes 21 are composed of holes having a diameterD=1.8 mm, for example, and are uniformly arranged in a lattice pointpattern at pitches p2 x=p2 y=5 mm. Incidentally, the small holes 21 arepreferably so formed as not to overlap with the slots 11. Besides, thearrangement of the small holes 21 is not limited to the lattice pointpattern, inasmuch as the small holes 21 are formed at predeterminedpitches over the entire surface area of the polishing pad.

In the second polishing pad 2, since there are provided the pluralitiesof slots 11 and small holes 21 piercing through the second polishing pad2 in the thickness direction, the hermetic seal property between thesurface to be polished and the surface of the second polishing pad 2 islowered due to the presence of the slots 11, so that a negative pressureis less liable to be generated there, like in the case of the firstpolishing pad 1. Therefore, it is easy to remove the work from thesurface of the second polishing pad 2 after completion of polishing. Inaddition, since the slots 11 reserve the polishing liquid therein, it ispossible to reduce the amount of the polishing liquid used.

Further, since the plurality of small holes 21 other than the slots 11are provided, the polishing resistance can be prevented from increasing.Furthermore, since grooves are not provided, unlike the related-artpolishing pads, there is no possibility that the polishing liquid mightflow out through grooves to the exterior of the polishing pad.

In addition, since the slots 11 and the small holes 21 formed in thesecond polishing pad 2 according to the present invention can be formedby a single punching operation, the production cost is lower than thatof a polishing pad provided with grooves by cutting.

Further, since the slots 11 and the small holes 21 are so formed as topierce through the second polishing pad 2 in the thickness direction,the slots 11 and the small holes 21 are not lost even when the secondpolishing pad 2 is worn as polishing proceeds. As a result, the secondpolishing pad 2 can show a prolonged pad life, as compared withpolishing pads provided with grooves.

Next, the possibility of generation of troubles during conveying ofpolishing pads was investigated by using the first and second polishingpads 1 and 2 and varying the length of the slots, the width of theslots, and the pitch in the width direction of the slots. The spacing din the longitudinal direction of the slots 11 shown in FIGS. 1 and 2 wasfixed at 10 mm. In each polishing, a silicon wafer provided on itssurface with a solid film of silicon oxide was used as a work, thesilicon oxide film as a surface to be polished was polished once, and itwas checked 10 times if the silicon wafer could conveyed. The resultsare summarized in Table 1 below. TABLE 1 IC1000/SUBA400 IC1000/SUBA400IC1000/SUBA400 IC1000/SUBA400 laminate laminate IC1000 IC1000 laminatelaminate Without With small holes monolayer monolayer Without With smallholes small holes Both slots and Length Width of Pitch of Without Withsmall holes Both slots and Slots piercing small holes of slots slotsslots small small Slots in IC1000 small holes in through piercingthrough (mm) (mm) (mm) holes holes only IC1000 only IC1000/SUBA400IC1000/SUBA400 10 2 40 0.3 0.8 0.4 1 0.4 1 20 0.5 10 0 0 0 0 0 0 1 20 00 0 0 0 0 2 100 0 0.2 0 0.3 0 0.4 40 0 0 0 0 0 0 25 0 0 0 0 0 0 20 0 0 00 0 0 10 0 0 0 0 0 0 30 2 40 0 0 0 0 0 0 40 2 0 0 0 0 0 0 50 2 0 0 0 0 00 Without slots 0.2 0.7 0.2 1 0.1 1

In the above investigation, a foamed polyurethane-made polishing pad(for example, the IC1000 monolayer product, 1.2 mm thick, produced byRodel Inc.) and a laminated polishing pad comprising a foamedpolyurethane-made upper layer and a PET (polyethyleneterephthalate)-made lower layer (for example, a laminated polishing padcomprising a 1.2 mm-thick upper layer formed of IC1000 produced by RodelInc. and a 1.2 mm-thick lower layer formed of SUBA400 produced by RodelInc.) were used as the first and second polishing pads 1 and 2.

The first and second polishing pads 1 and 2 were each adhered to apolishing surface plate (not shown) by use of a double-faced pressuresensitive adhesive tape in the case where the polishing pad was amonolayer product. In the above investigation, in order that a slurrydoes not make direct contact with the polishing surface plate, the firstand second polishing pads 1 and 2 were provided with slots 11, smallholes 21 or the like by punching, and then were each adhered to thepolishing surface plate by use of a double-faced pressure sensitiveadhesive tape. Incidentally, when the double-faced pressure sensitiveadhesive tape is adhered to the first and second polishing pads 1 and 2and then they are provided with the slots 11, the small holes 21 or thelike by punching, combinations of the polishing pad and the pressuresensitive adhesive tape with the holes formed also in the pressuresensitive adhesive tape are obtained. Even where the double-facedpressure sensitive adhesive tape is thus also provided with the slots 11and/or the small holes 21, the effects of the present invention are notthereby influenced at all.

On the other hand, the laminated products (laminates) prepared includedthose provided with holes piercing through IC1000 only and those withholes piercing through both IC1000 and SUBA400. Since IC1000 and SUBA400are adhered by use of the double-faced pressure sensitive adhesive tape,the laminated product with holes piercing through IC1000 only can beobtained when IC1000 is provided with the holes by punching beforeadhesion, whereas the laminate product with holes piercing through bothIC1000 and SUBA400 can be easily obtained when formation of the holes bypunching is conducted after adhesion.

IC1000 was adhered to SUBA400 by use of a double-faced pressuresensitive adhesive tape. In this case, of the laminate products withholes piercing through IC1000 only, those with the double-faced pressuresensitive adhesive tape being not provided with holes can be obtainedwhen punching is conducted before adhesion of the double-faced pressuresensitive adhesive tape to IC1000, whereas those with the double-facedpressure sensitive adhesive tape being provided with holes can beobtained when punching is conducted after adhesion of the double-facedpressure sensitive adhesive tape. The effects of the present inventionare not affected by whether or not the double-faced pressure sensitiveadhesive is provided with holes. In the investigation, the laminatedproducts with the double-faced pressure sensitive adhesive tape beingfree of holes were prepared and used, in view of that such laminatedproducts are free of penetration of the slurry to the lower layer formedof SUBA400.

The laminated products with holes piercing through both IC1000 andSUBA400 were each adhered to the polishing surface plate by use of adouble-faced pressure sensitive adhesive tape. Of the laminatedproducts, those with the double-faced pressure sensitive adhesive tapebeing not provided with holes can be obtained when punching is conductedbefore adhesion of the double-faced pressure sensitive adhesive tape,whereas those with the double-faced pressure sensitive adhesive tapebeing provided with holes can be obtained when punching is conductedafter adhesion of the double-faced pressure sensitive adhesive tape. Theeffects of the present invention are not influenced by whether or notthe double-faced pressure sensitive adhesive tape is provided withholes. In the investigation, the laminated products with thedouble-faced pressure sensitive adhesive tape being free of holes wereprepared and used, in view of that such laminated products are free ofdirect contact of the slurry with the polishing surface plate.

From Table 1 it is seen that, in the case where the first polishing pad1 composed of an IC1000 monolayer had been provided with slots 11 havinga length of not less than 20 mm, no error was generated in conveying thewafer. However, it should be noted here that, in the case of the secondpolishing pad 2 provided with both small holes 21 as well as slots 11, aconveying error was generated when the pitch p of the slots 11 reachedor exceeded 100 mm.

In addition, in the case of the first polishing pad 1 composed of anIC1000-SUBA400 laminate and provided with slots 11 piercing through onlyIC1000, no error was generated in conveying the wafer when the length ofthe slots 11 was not less than 20 mm. In the case of the secondpolishing pad 2 provided with small holes 21 as well as slots 11,however, a conveying error was generated when the pitch p of the slots11 reached or exceeded 100 mm.

In addition, in the case of the first polishing pad 1 composed of anIC1000-SUBA400 laminate and provided with slots 11 piercing through bothIC1000 and SUBA400, no error was generated in conveying the wafer whenthe length of the slots 11 was not less than 20 mm. In the case of thesecond polishing pad 2 provided with small holes 21 as well as slots 11,however, a conveying error was generated when the pitch p of the slots11 reached or exceeded 100 mm.

Besides, in the lowermost row of Table 1, the results obtained with thepolishing pads not provided with slots 11 are shown as a comparativeexample. As a result, a wafer conveying error was generated,irrespectively of whether the polishing pad was a monolayer product or alaminate and whether or not the polishing pad was provided with smallholes. This shows that the presence of the slots 11 is effective forpreventing the wafer conveying errors from being generated.

Accordingly, it has been found out that the length of the slots 11should be not less than 20 mm. Further, it was also found that the pitchp in the width direction of the slots should be less than 100 mm.Besides, the lower limit of the width of the slots 11 was set to betwice the width of the slots 11, taking into account the rigidity of thepolishing pad in the areas between the slots 11.

Next, an embodiment of slots formed in the first and second polishingpads according to the present invention will be described referring tothe plan view shown in FIG. 3.

As shown in FIG. 3, the first polishing pad 1 (the second polishing pad2) may be provided with slots 11 which are arranged radially. While thepolishing pad provided with one slot 11 in a radial direction is shownin the figure, the polishing pad may be provided with a plurality ofslots in a radial direction. Besides, while small holes 21 are omittedin FIG. 3, the polishing pad may be provided with small holes 21, as hasbeen described referring to FIG. 2. Incidentally, the arrangement of thesmall holes 21 is not limited to the lattice point pattern, inasmuch asthe small holes 21 are formed at predetermined pitches over the entiresurface area of the polishing pad.

In the polishing pad configured as above-described, by providing theslots 11 with a sufficient length, for example, a length greater thanthe radius of the work (e.g., wafer) and arranging the slots 11radially, it is possible to obtain a structure which ensures that anegative pressure is less liable to be generated on the wafer. With suchslots 11 formed by punching, the slots 11 can be formed in acomparatively freer shape, as compared with grooves. This is one of theadvantages of the present configuration.

Next, another embodiment of the slots formed in the first and secondpolishing pads according to the present invention will be describedreferring to the plan view shown in FIG. 4.

As shown in FIG. 4, the first polishing pad 1 (the second polishing pad2) may be provided with circular arc-shaped slots 11 which are arrangedconcentrically, for example. While the case where two rows of the slots11 are formed concentrically is shown in the figure, the slots 11 may beformed in three or more rows. Besides, while small holes 21 are omittedin FIG. 4, the polishing pad may be provided with small holes 21, as hasbeen described referring to FIG. 2. Incidentally, the arrangement of thesmall holes 21 is not limited to the lattice point pattern, inasmuch asthe small holes 21 are formed at predetermined pitches over the entiresurface area of the polishing pad.

In the polishing pad configured as above, by setting the length of theslots 11 to be, for example, sufficiently greater than the radius of thework (e.g., wafer) and forming the slots 11 in an arcuate shape, it ispossible to obtain a structure which ensures that a negative pressure isless liable to be generated on the wafer and that the slurry holdingproperty is enhanced, as compared with the cases of a parallel or radialarrangement, whereby the amount of the slurry used can be reduced. Withthe slots 11 and the small holes 21 thus formed by punching, they can beformed in comparatively freer shape, as compared with grooves. This isone of the advantages of the present configuration.

Next, a second embodiment of the first polishing pad according to thepresent invention will be described referring to the plan view shown inFIG. 5. In FIG. 5, there is shown a rectangular polishing pad, as usedon a belt-type polishing apparatus. Incidentally, small holes areomitted in the plan view.

As shown in FIG. 5, the polishing pad 5 is provided with a plurality ofslots 11 piercing through the polishing pad 5 in the thicknessdirection, the slots 11 being aligned in the row direction and thecolumn direction. The polishing pad 5 is formed, for example, of a resinsuch as foamed urethane and urethane. The thickness of the polishing pad5 is comparable to those of ordinary polishing pads, and is about 0.5 to3.0 mm, for example. The slots 11 are included in the polishing pad 5,and the length L in the longitudinal direction thereof is not less than20 mm. Besides, the slots 11 are formed at a pitch p which is not lessthan twice the length W in the transverse direction thereof (hereinafterreferred to as width) and is less than 100 mm. Incidentally, the spacingd in the longitudinal direction of the slots 11 is appropriately set;here, the spacing d is set to be 10 mm, as an example. In addition, theslots 11 may be formed to be staggered from each other in either one orboth of the row direction and the column direction.

Next, a second embodiment of the second polishing pad according to thepresent invention will be described referring to the plan view and thepartly enlarged view shown in FIG. 6. Incidentally, small holes areomitted in the plan view. The symbols to be used in the followingdescription are the same as those used in FIGS. 2 and 5.

As shown in FIG. 6, the polishing pad 6 according to this secondembodiment is the polishing pad 5 as described referring to FIG. 5 whichis provided with the same small holes 21 as described referring to FIG.2. Namely, the polishing pad 6 is provided with slots 11 piercingthrough the polishing pad 6 in the thickness direction in the state ofbeing aligned, for example, in the row direction and the columndirection, and is provided also with a plurality of small holes 21piercing through the polishing pad 6 in the thickness direction andhaving a diameter D of not more than 10 mm, preferably not more than 5mm. Specifically, the slots 11 are included in the polishing pad 6, havea length L of not less than 20 mm, and are formed at a pitch p1 which isnot less than twice the width W thereof and is less than 100 mm.Incidentally, the spacing d in the longitudinal direction of the slots11 is appropriately set; here, the spacing d is set to 10 mm, as anexample. Besides, the slots 11 may be formed to be staggered from eachother in either one or both of the row direction and the columndirection.

Furthermore, the small holes 21 are composed of holes having a diameterD=1.8 mm, for example, and are uniformly arranged in a lattice pointpattern with pitches p2 x=p2 y=5 mm. Incidentally, it is preferable thatthe small holes 21 are so formed as not to overlap with the slots 11. Inaddition, the arrangement of the small holes 21 is not limited to thelattice point pattern, inasmuch as the small holes 21 are formed atpredetermined pitches over the entire surface area of the polishing pad.

While the slots 11 are formed in parallel to the driving direction ofthe belt in the above configuration, the direction in which the slots 11are arranged may be slant relative to the belt driving direction orperpendicular to the belt driving direction.

While the case where the slots 11 and the small holes 21 are formed by asingle punching operation has been described in the above-describedembodiments, the slots 11 and the small holes 21 may be formed bypunching independently from each other. Such a method promises easierproduction of the polishing pad in the cases where it is desired, forexample, to enlarge the width of the slots 11 as compared with the pitchof the small holes 21. Specific examples of such cases include a casewhere it is desired to form the small holes 21 at a pitch of 5 mm and toform slots 11 having a width of 7 mm. Another example is a case wherethe slots 11 and the small holes 21 overlap with each other in an areaor areas. Specific example of this is a case where the small holes 21are arranged in a lattice point pattern and the slots 11 are arrangedradially or in a circular arc-shaped pattern.

In addition, where the polishing pad is provided with a window foroptical detection of an end point, it is preferable to form no hole inthe window portion, for ensuring that the light incident on the wafer isnot intercepted. However, provision of the window with holes would notchange the effectiveness of the present invention.

While IC1000 has been used as an example of the polishing pad in theabove-described embodiments, the same effects as above-mentioned can beobtained irrespectively of the material of the polishing pad, namely, byusing a nonwoven fabric-made polishing pad, sueded polishing pad, orother resin-made polishing pad or the like which is commerciallyavailable. In addition, even where a polishing pad comprising fixedabrasive grains is used, the effectiveness of the present inventionremains unchanged, and the same effects as above-mentioned can beobtained.

Next, the polishing apparatuses according to the present invention willbe described referring to the schematic configurational perspectiveviews shown in FIGS. 7 and 8.

The first polishing apparatus is a polishing apparatus for polishing asurface to be polished of a material to be polished, by bringing apolishing pad into contact with the surface and into a frictional motionrelative to the surface, wherein the polishing apparatus comprises oneof the above-described polishing pads 1 to 4.

Specifically, as shown in FIG. 7, the first polishing apparatus 101comprises a polishing surface plate 111 which can be turned in thedirection of arrow a, for example. The polishing surface plate 111 isturned through a rotary shaft 112 connected to a turning drive which isnot shown. In addition, one of the polishing pads 1 to 4 described abovereferring to FIGS. 1 to 4 is mounted on the polishing surface plate 111.Here, the polishing pad 1 was mounted. Now, description will be madereferring to the polishing pad 1. The polishing pad 1 is mounted by ageneral polishing pad mounting method, for example, a method using apressure sensitive adhesive sheet (inclusive of pressure sensitiveadhesive tape) or a pressure sensitive adhesive. Specifically, theabove-described method is adopted.

A polishing head 115 is provided at a position opposed to the polishingsurface plate 111 on which the polishing pad 1 is mounted, generally inopposition to a position deviated from the center of rotation of thepolishing surface plate 111. The polishing head 115 can be freely raisedand lowered. Further, the polishing pad 115 is turned, for example, inthe direction of arrow b, through a rotary shaft 116 connected to aturning drive which is not shown. In addition, the surface opposed tothe polishing surface plate 111, of the polishing head 115 is sodesigned as to mount a work 301 thereon. As the method for mounting thework, various methods can be adopted, such as vacuum suction,electrostatic attraction, adhesion by use of an adhesive, adhesion byuse of a pressure sensitive adhesive sheet, etc. Furthermore, a nozzle121 for supplying a polishing slurry 131 (indicated by an arrow, forconvenience) onto the polishing pad 1 is provided on the upper side ofthe polishing surface plate 111 and in the vicinity of the polishinghead 115. The polishing slurry 131 is so supplied as to come between thepolishing pad 1 and the work 301 as the polishing surface plate 111 isturned.

The first polishing method according to the present invention will bedescribed below. As an example, the method of polishing by use of theabove-described first polishing apparatus 101 will be described. First,a desired one of the polishing pads 1 to 4 is mounted on the polishingsurface plate 111. In addition, the work 301 is mounted on the polishinghead 115. Thereafter, the polishing slurry 131 is supplied from thenozzle 121 onto the polishing pad 1, and the polishing surface plate 111is turned. Besides, the polishing head 115 is also turned. Then, thework 301 is brought into contact with the polishing pad 1 so as toobtain a desired processing pressure, whereby the surface to be polishedof the work 301 is polished. As an example of the polishing conditions,a potassium hydroxide (KOH)-based fumed silica slurry was used as thepolishing slurry 131, the processing pressure was set at 300 g/cm², andthe rotating speeds were so set that the circumferential speed of thepolishing pad relative to the work (e.g., wafer) was 60 m/min. After thepolishing is finished, the work 301 is separated from the polishing pad1, the supply of the polishing slurry 131 is stopped, and the turningsof the polishing surface plate 111 and the polishing head 115 arestopped. Thereafter, the work 301 may be detached from the polishinghead 115. Incidentally, the polished surface of the work 301 may bewashed before the detachment.

The second polishing apparatus is a belt-type polishing apparatus forpolishing a surface to be polished of a material to be polished, bybringing a polishing pad into contact with the surface and into africtional motion relative to the surface, wherein the polishingapparatus comprises one of the above-described polishing pads 5 and 6.

Specifically, as shown in FIG. 8, the second polishing apparatus 201comprises turnable rollers 211 and 212 disposed in parallel to eachother, and the polishing pad 5 or 6 described above referring to FIG. 5or 6 of the belt type which is wrapped around the rollers 211 and 212.Here, as an example, the polishing pad 5 is used. Description will bemade below referring to the polishing pad 5. The polishing pad 5 isstretched in a deflection-free state by the rollers 211 and 212. Inaddition, it is preferable to provide, between the rollers 211 and 212,a guide (not shown) which is for preventing the polishing pad fromdeflecting toward the inside, i.e., for internally supporting thepolishing pad toward the polishing head 215 and on which the polishingpad can be freely slid. Besides, at least either one of the rollers 211and 212 turned by a turning drive in the direction of arrow c, forexample. This turns the polishing pad 4 in the direction of arrow d.

A polishing head 215 is provided opposite to the polishing surface ofthe polishing pad 5. The polishing head 215 is designed to be freelyraised and lowered. Further, the polishing head 215 is turned through arotary shaft 216 connected to a turning drive which is not shown. Inaddition, the surface opposed to the polishing pad 5, of the polishinghead 215 is so designed as to mount a work 301 thereon. As the methodfor mounting the work 301, a variety of methods can be adopted, such asvacuum suction, electrostatic attraction, adhesion by use of anadhesive, adhesion by use of a pressure sensitive adhesive sheet, etc.Furthermore, a nozzle 221 for supplying a polishing slurry 231(indicated by an arrow, for convenience) onto the polishing pad 5 isprovided on the upper side of the polishing pad 5 and in the vicinity ofthe polishing head 215. The polishing slurry 231 is so supplied as tocome between the polishing pad 5 and the work 301 as the rollers 211 and212 are turned.

The second polishing method according to the present invention will bedescribed below. As an example, the method of polishing by use of theabove-described second polishing apparatus 201 will be described. First,a desired one of the polishing pads 5 and 6 is selected. Here, thepolishing pad 5 is used. Therefore, description will be made belowreferring to the polishing pad 5. In addition, a work 301 is mounted onthe polishing head 215. Thereafter, the polishing slurry 231 is suppliedfrom the nozzle 221 onto the polishing pad 5, and the rollers 211 and212 are turned to turn the polishing pad 5. Besides, the polishing head215 is also turned. Then, the work 301 is brought into contact with thepolishing pad 5 so as to obtain a desired processing pressure, wherebythe surface to be polished of the work 301 is polished. As an example ofpolishing conditions, a potassium hydroxide (KOH)-based fumed silicaslurry was used as the polishing slurry 231, the processing pressure wasset at 300 g/cm², and the rotating speeds were so set that thecircumferential speed of the polishing pad relative to the work (e.g.,wafer) was 60 m/min. After the polishing is over, the work 301 isseparated from the polishing pad 5, the supply of the polishing slurry231 is stopped, and the turnings of the polishing pad 5 (the rollers 211and 212) and the polishing head 215 are stopped. Thereafter, the work301 may be detached from the polishing head 215. Incidentally, thepolished surface of the work 301 may be washed before the detachment.

The above-described polishing methods are mere examples, and thepolishing conditions can be appropriately modified according to theobject of polishing. In addition, conventionally used polishingconditions may also be used.

As has been described above, according to the first polishing pad of thepresent invention, the polishing pad is provided with a plurality ofslots piercing through the polishing pad in the thickness direction, sothat it is possible to lower the hermetic seal property between thesurface to be polished and the polishing pad surface, thereby ensuringthat a negative pressure is less liable to be generated there.Therefore, the work can be easily removed from the polishing pad surfaceafter completion of polishing. In addition, since the slots can beformed by punching, the polishing pad is lower in production cost than arelated-art polishing pad provided with grooves formed by a related-artcutting operation. Further, since the slots are so formed as to piercethrough the polishing pad in the thickness direction, the slots are notlost even when the polishing pad is worn, so that the polishing pad canshow a prolonged pad life, as compared with the polishing pads providedwith grooves.

According to the second polishing pad of the present invention, thepolishing pad is provided with a plurality of holes piercing through thepolishing pad in the thickness direction, and part of the plurality ofholes are composed of slots, so that the same effects as those of thefirst polishing pad can be obtained. Further, since a plurality of holesother than the slots are present, it is possible to prevent thepolishing resistance from increasing. Furthermore, since the slots canreserve the polishing liquid therein, the amount of the polishing liquidused can be reduced, as compared to the cases of the grooved polishingpads according to the Related Art. In addition, since the plurality ofholes inclusive of the slots can be formed by a single punchingoperation, the production cost of the polishing pad is lowered, ascompared with the cases of the related-art polishing pads provided withgrooves by cutting. Furthermore, since the slots are so formed as topierce through the polishing pad in the thickness direction, the slotsare not lost even when the polishing pad is worn, so that the polishingpad can show a prolonged pad life, as compared with the polishing padsprovided with grooves.

According to the polishing apparatuses of the present invention, theoperating cost of the polishing apparatus can be lowered, since thepolishing pad according to the present invention which can be producedat a lower cost is mounted thereon. Further, since the polishing padaccording to the present invention is longer in pad life than thegrooved polishing pads according to the Related Art, it is possible tolower the frequency of replacement of the polishing pad. As a result,the operating cost of the polishing apparatus can be lowered. Inaddition, it is possible to obtain the functions and effects of thepolishing pads according to the present invention.

The polishing method according to the present invention promises areduction in polishing cost, since the polishing pad according to thepresent invention which can be produced at a lower cost is used in themethod. Furthermore, since the polishing pad according to the presentinvention is longer in pad life than the related-art polishing padsprovided with grooves, it is possible to reduce the frequency ofreplacement of the polishing pad. As a result, polishing cost can bereduced. In addition, the functions and effects of the polishing padsaccording to the present invention can be obtained.

1-18. (canceled)
 19. A method of forming a polishing pad for polishing asurface of a material to be polished, comprising: providing a polishingpad; and forming slots in the polishing pad which extend through theentire thickness of said polishing pad in the thickness direction suchthat the slot opening on one surface of the pad is substantially thesame size and shape as the slot opening on the opposing surface of thepad, and wherein the slots do not extend to an outer circumferentialsurface of the pad.
 20. A method of forming a polishing pad forpolishing a surface of a material to be polished, comprising: providinga polishing pad; and forming holes in the polishing pad which extendthrough the entire thickness of said polishing pad in the thicknessdirection, part of said plurality of holes being composed of slots andwherein the slots do not extend to an outer circumferential surface ofthe pad, and wherein each slot opening on one surface of the pad issubstantially the same size and shape as the slot opening on theopposing surface of the pad.
 21. A method of forming a polishing pad asset forth in claim 20, wherein the holes and the slots do not overlap.22. A method of forming a polishing pad as set forth in claim 19,wherein the formation of the slots in the polishing pad is comprised ofpunching the slots into the polishing pad.
 23. A method of forming apolishing pad as set forth in claim 20, wherein the formation of theslots in the polishing pad is comprised of punching the slots into thepolishing pad.